Natural Selection In Humans

Augustine Kong and colleagues report, in the February issue of Nature Genetics, evidence for natural selection acting on the human genome. The Icelandic study found that one orientation of a particular chromosome segment, which is rare in much of the world, has reached a frequency of 20% in some European populations. The authors find that this variant, called a chromosome inversion, is still undergoing positive selection in Icelandic pedigrees and conclude that it has a positive effect on fertility. While the effect is modest - Icelandic people with the variant have 3.2% more children per generation - it is large enough to have profound consequences on an evolutionary timescale.